The present invention relates to beam-forming apparatus and methods, and elongated beams manufactured using same, and more particularly relates to multi-strip beams and related apparatus and methods for forming automotive bumper reinforcement beams from multiple strips. However, a scope of the present invention is not limited to bumper reinforcement beams nor automotive uses.
Modern vehicles include bumper systems with reinforcement beams that must pass stringent performance requirements (e.g. test standards that measure torsional and bending impact strengths, various barrier impacts, vehicle to vehicle and pedestrian impacts), but also meet industry standards that place a premium on minimizing weight (e.g. mpg standards). Also, the competitiveness of the industry requires minimizing manufacturing cost while providing high dimensional consistency, reliability of manufacture, and design and manufacturing flexibility.
Bumper reinforcement beams are used to provide cross car structure to bumper systems, and are often made by roll forming and/or extrusion processes. Roll forming can provide a competitive process cost with good part quality when used in high volume runs. However, most high-volume commercial roll forming processes are limited to constant cross-sectional shapes, are limited to forming a single sheet of material, require significant lead time to develop the forming rolls, and require substantial investment in heavy-duty roll forming equipment. Secondary processes have been used to reshape portions of roll formed beams, but secondary processes are expensive, slow, often not dimensionally consistent, require multiple handling of in-process parts, and can be manually intensive.
Extruded aluminum beams are sometimes specified by original equipment manufacturers (called OEMs) due to their light weight, high strength-to-weight ratio, and the ability of extruded aluminum beams to have walls with different thicknesses located for optimal performance. However, aluminum is an expensive material, and further extrudable grades of aluminum are limited in tensile strength and are generally high in cost. Also, aluminum beams have constant cross sections along their full length, due to the extruding process. Also, beams made using extrusion processes require secondary operations, such as beam-curving (i.e. “sweeping”), hole-punching (e.g. for bracket attachment or for attachment holes or clearance holes), and aging/thermal-treatment of the material (for strength and stability).
An improvement is desired that provides flexibility of part design (including use of optimally-placed wall materials, varied wall thicknesses and shapes), but that also provides process savings/improvements in terms of low cost, relatively lower capital investment, high efficiency of manufacture, good reliability, high dimensional consistency, and low in-process inventory. It is desirable to use forming and bonding processes that are known and non-exotic.